/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.table.factories.datagen.types;

import org.apache.flink.annotation.Internal;
import org.apache.flink.api.common.functions.RuntimeContext;
import org.apache.flink.runtime.state.FunctionInitializationContext;
import org.apache.flink.streaming.api.functions.source.datagen.DataGenerator;

import java.io.Serializable;
import java.util.function.Function;

/**
 * Utility for mapping the output of a {@link DataGenerator}.
 */
@Internal
public class DataGeneratorMapper<A, B> implements DataGenerator<B> {

	private final DataGenerator<A> generator;

	private final SerializableFunction<A, B> mapper;

	public DataGeneratorMapper(DataGenerator<A> generator, SerializableFunction<A, B> mapper) {
		this.generator = generator;
		this.mapper = mapper;
	}

	@Override
	public void open(String name, FunctionInitializationContext context, RuntimeContext runtimeContext) throws Exception {
		generator.open(name, context, runtimeContext);
	}

	@Override
	public boolean hasNext() {
		return generator.hasNext();
	}

	@Override
	public B next() {
		return mapper.apply(generator.next());
	}

	/**
	 * A simple serializable function.
	 */
	public interface SerializableFunction<A, B> extends Function<A, B>, Serializable {}
}
